127 lines
4.0 KiB
JavaScript
127 lines
4.0 KiB
JavaScript
/*
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This file is part of ethereum.js.
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ethereum.js is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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ethereum.js is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with ethereum.js. If not, see <http://www.gnu.org/licenses/>.
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*/
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/** @file httprpc.js
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* @authors:
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* Marek Kotewicz <marek@ethdev.com>
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* Marian Oancea <marian@ethdev.com>
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* @date 2014
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*/
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// TODO: is these line is supposed to be here?
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if (process.env.NODE_ENV !== 'build') {
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var XMLHttpRequest = require('xmlhttprequest').XMLHttpRequest; // jshint ignore:line
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}
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/**
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* HttpRpcProvider object prototype is implementing 'provider protocol'
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* Should be used when we want to connect to ethereum backend over http && jsonrpc
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* It's compatible with cpp client
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* The contructor allows to specify host uri
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* This provider is using in-browser polling mechanism
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*/
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var HttpRpcProvider = function (host) {
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this.handlers = [];
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this.host = host;
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};
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/// Transforms inner message to proper jsonrpc object
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/// @param inner message object
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/// @returns jsonrpc object
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function formatJsonRpcObject(object) {
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return {
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jsonrpc: '2.0',
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method: object.call,
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params: object.args,
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id: object._id
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};
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}
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/// Transforms jsonrpc object to inner message
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/// @param incoming jsonrpc message
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/// @returns inner message object
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function formatJsonRpcMessage(message) {
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var object = JSON.parse(message);
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return {
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_id: object.id,
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data: object.result,
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error: object.error
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};
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}
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/// Prototype object method
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/// Asynchronously sends request to server
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/// @param payload is inner message object
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/// @param cb is callback which is being called when response is comes back
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HttpRpcProvider.prototype.sendRequest = function (payload, cb) {
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var data = formatJsonRpcObject(payload);
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var request = new XMLHttpRequest();
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request.open("POST", this.host, true);
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request.send(JSON.stringify(data));
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request.onreadystatechange = function () {
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if (request.readyState === 4 && cb) {
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cb(request);
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}
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};
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};
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/// Prototype object method
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/// Should be called when we want to send single api request to server
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/// Asynchronous
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/// On response it passes message to handlers
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/// @param payload is inner message object
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HttpRpcProvider.prototype.send = function (payload) {
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var self = this;
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this.sendRequest(payload, function (request) {
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self.handlers.forEach(function (handler) {
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handler.call(self, formatJsonRpcMessage(request.responseText));
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});
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});
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};
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/// Prototype object method
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/// Should be called only for polling requests
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/// Asynchronous
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/// On response it passege message to handlers, but only if message's result is true or not empty array
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/// Otherwise response is being silently ignored
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/// @param payload is inner message object
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/// @id is id of poll that we are calling
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HttpRpcProvider.prototype.poll = function (payload, id) {
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var self = this;
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this.sendRequest(payload, function (request) {
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var parsed = JSON.parse(request.responseText);
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if (parsed.error || (parsed.result instanceof Array ? parsed.result.length === 0 : !parsed.result)) {
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return;
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}
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self.handlers.forEach(function (handler) {
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handler.call(self, {_event: payload.call, _id: id, data: parsed.result});
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});
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});
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};
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/// Prototype object property
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/// Should be used to set message handlers for this provider
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Object.defineProperty(HttpRpcProvider.prototype, "onmessage", {
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set: function (handler) {
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this.handlers.push(handler);
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}
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});
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module.exports = HttpRpcProvider;
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